BS EN 14108 Fat and oil derivatives - Fatty Acid Methyl Esters (FAME) - Determination of sodium content by atomic absorption spectrometry
3 Reagents
Use only reagents of recognised analytical grade, unless otherwise specified.
3.1 Recommendations for washing glassware
The glassware used for the preparation of the solutions shall be washed at least twice with an approximate 5 mol/l solution of hydrochloric acid, rinsed with distilled water then dried in order to avoid sodium pollution.
3.2 Xylene (mixture of isomers)
WARNING - Inflammable and noxious.
3.3 Stock oil 75 (75 mm2/s)
3.4 Stock oil solution in xylene (200 g/l); dilute in a 200 ml volumetric flask, 40 g of stock oil (3.3) with xylene. Store this solution in a polypropylene bottle.
3.5 Sodium, solution in oil (5000 mg/kg). Ready-to-use solution of a sodium organometallic salt in stock oil, having a certified titre.
3.6 Sodium, solutions of intermediary dilutions for the preparation of the set of calibration solutions.
3.6.1 Sodium, solution in xylene (500 mg/l): weigh, to within 0.001 g, approximately 2.5 g of the sodium solution (3.5) in a 25 ml volumetric flask and dilute to the mark with xylene.
This solution may be stored for a month.
3.6.2 Sodium, solution in xylene (5 mg/l): sample, using a pipette, 0.50 ml of the sodium standard solution (3.6.1), transfer into a 50 ml volumetric flask and dilute to the mark with xylene.
Prepare a new solution each day.
NOTE The solutions of intermediary dilutions may be prepared in glass flasks (the sodium pollution being negligible at these contents).
4 Apparatus
4.1 Atomic absorption spectrometer
Any atomic absorption spectrometer may be used provided that it is equipped with:
4.1.1 A hollow sodium cathode lamp.
4.1.2 A nebulization system suited for the organic solutions, of which the materials are solvent-resistant.
4.1.3 A burner head capable of being used with organic solutions and an air-acetylene flame.
4.2 Balance, with an accuracy of 1 mg.
4.3 Glassware
4.3.1 25 ml and 50 ml volumetric flasks.
4.3.2 0.5 ml graduated precision pipette.
4.4 Polypropylene ware
4.4.1 50 ml and 200 ml volumetric flasks.
4.4.2 10 ml pipette.
4.4.3 250 ml bottles.
4.4.4 Automatic pipette having a variable volume of 1 ml to 5 ml, fitted with ejectable and disposable polypropylene tips.
